Well, FB is there for a long time, so the whole prospect of Snapchat relies on that Facebook shows mercy not to copy their feature? That sounds like a horrible business to begin with.
Seems like the best you are hoping for is that you end up entrenched before they react (like twitch vs youtube).
And I don't really understand when Twitter has set a bad precedent for social media companies, why people still bet on Snapchat. Weird choice.